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| author | Christian Krinitsin <mail@krinitsin.com> | 2025-05-30 16:52:07 +0200 |
|---|---|---|
| committer | Christian Krinitsin <mail@krinitsin.com> | 2025-05-30 16:52:17 +0200 |
| commit | 9260319e7411ff8281700a532caa436f40120ec4 (patch) | |
| tree | 2f6bfe5f3458dd49d328d3a9eb508595450adec0 /gitlab/issues_text/target_missing/host_missing/accel_missing/1128 | |
| parent | 225caa38269323af1bfc2daadff5ec8bd930747f (diff) | |
| download | qemu-analysis-9260319e7411ff8281700a532caa436f40120ec4.tar.gz qemu-analysis-9260319e7411ff8281700a532caa436f40120ec4.zip | |
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Diffstat (limited to 'gitlab/issues_text/target_missing/host_missing/accel_missing/1128')
| -rw-r--r-- | gitlab/issues_text/target_missing/host_missing/accel_missing/1128 | 24 |
1 files changed, 24 insertions, 0 deletions
diff --git a/gitlab/issues_text/target_missing/host_missing/accel_missing/1128 b/gitlab/issues_text/target_missing/host_missing/accel_missing/1128 new file mode 100644 index 000000000..ebd6be401 --- /dev/null +++ b/gitlab/issues_text/target_missing/host_missing/accel_missing/1128 @@ -0,0 +1,24 @@ +PPC: `spr_write_xer` doesn't set flag bits in `cpu_xer` +Description of problem: +`spr_write_xer()` does not set the `ca`, `ov`, `so`, `ca32`, `ov32` etc. flag bits in the `cpu_xer` variable. + +In fact it copies all bits from the source `GPR` and _excludes_ each flag bit. + +This is not a problem for execution since `spr_read_xer()` gets the flag bits from `cpu_ca/ov/so...` and not from `cpu_xer`. + +Nonetheless it is problem for tools which trace the execution in QEMU (e.g. https://github.com/BinaryAnalysisPlatform/qemu). + +A fix would be to remove the `~` in https://gitlab.com/qemu-project/qemu/-/blob/master/target/ppc/translate.c#L481 +Steps to reproduce: +Haven't found out yet how to debug QEMU so the TCGv values can be investigated. But in general one need to: + +- Execute a binary which executes something like: +``` +r4 = 0xffffffffffffffff +mtxer r4 +``` +and check the `cpu_xer` value after the `xer` write. + +Checking the debug logs (`in_asm,cpu`) doesn't work, since the `xer` value in the logs is not taken directly from `cpu_xer`. +Additional information: +Code ref: https://gitlab.com/qemu-project/qemu/-/blob/master/target/ppc/translate.c#L480-L483 |